Split Air con

[bazzabear]

As I understand things:

At the moment electricity is far more expensive than gas per kWh. Because of this, using air conditioning for heating is expensive compared to gas fired central heating.

But - electric heating is far more energy efficient than gas heating. So if electricity prices drop compared to gas - which they inevitably will at some point, as we are guided away from using a fossil fuel - then this will change.

 

[CaptainRAVE]

As above. In terms of transfer of energy, far more efficient than gas. However, electricity is more expensive. I definitely noticed our electricity bill increase when my wife decided to pump out a load of extra heat using our system. For air conditioning though, super cheap, barely noticeable.

 

[squerble]

Thanks both, so it looks like the future will be ground/air source heat pump with an air-to-water system powering the rads for heating and hot water tank, and then add split system for those rooms that you want the cooling in (lounge, office, bedroom etc.)?

 

[RJC]

My multi split has been ordered and should be here Mid September if all goes well - just in time for winter

Least ready for next year.

 

[CaptainRAVE]

My multi split has been ordered and should be here Mid September if all goes well - just in time for winter

Least ready for next year.

You’ll appreciate it on the 30C+ days next year. Easier to get it now than when the demand shoots up in the summer. I’m still using ours a fair bit.

 

[Matthew.M]

Are these split systems suitable for replacing your heating system? Ie. if you had 2-3 external wall units would that likely be enough to have a cassette in each room?

And if so, is this an efficient way of doing it? I believe using an air-to-water air source heat pump is the best way as it'd join up to your existing radiator system (though you may need to replace the radiators in some cases) or under-floor heating loops, and could also heat a hot-water tank. That said, you'd lose air conditioning this way and I think I'd realistically like air conditioning in at least 3 rooms.

Is the future going to be a combination of air/ground source heat pump systems with some split systems for cooling?

Most air con units are actually more efficient heaters than coolers, as the way the systems operate with the large external condenser favours heating. I think my unit is 4.5x multiplier electricity:heat and 4x for cooling, so only financially makes sense if electricity was less than 4x the cost, which at my rates it isn’t.

There are some caveats to the efficiency point, as if it gets too cold outside the multiplier will drop. But this is unlikely to happen in the UK as our winters are quite mild and the machines can be specified to suit.

 

[bazzabear]

One question, in preparation to having a system fitted:

Is house air-con like car air-con, in that you should make you you use it regularly to stop seals drying out and the like?

 

[Matthew.M]

One question, in preparation to having a system fitted:

Is house air-con like car air-con, in that you should make you you use it regularly to stop seals drying out and the like?

No. Cars lose gas as the compressor is driven by a mechanical link to the engine. The seals/gaskets around this shaft dry up and leak, but you need a method to transfer the rotational force to the aircon compressor.

Fixed/electrical compressors can be completely sealed around the motor. This is the same as freezer/fridge - these don’t lose gas if they’re not used as the motor is within the compressor housing.

I do wonder if this means EV/hybrid aircon systems also won’t need regassing in the same manner as older petrol/diesel cars, but that’s probably a tangent for this thread!

 

[James Peach]

Are these split systems suitable for replacing your heating system? Ie. if you had 2-3 external wall units would that likely be enough to have a cassette in each room?

And if so, is this an efficient way of doing it? I believe using an air-to-water air source heat pump is the best way as it'd join up to your existing radiator system (though you may need to replace the radiators in some cases) or under-floor heating loops, and could also heat a hot-water tank. That said, you'd lose air conditioning this way and I think I'd realistically like air conditioning in at least 3 rooms.

Is the future going to be a combination of air/ground source heat pump systems with some split systems for cooling?

I *believe* so. And I heard it's cheaper. But will have to wait until winter to let you know.

 

[andy_mk3]

No. Cars lose gas as the compressor is driven by a mechanical link to the engine. The seals/gaskets around this shaft dry up and leak, but you need a method to transfer the rotational force to the aircon compressor.

Fixed/electrical compressors can be completely sealed around the motor. This is the same as freezer/fridge - these don’t lose gas if they’re not used as the motor is within the compressor housing.

I do wonder if this means EV/hybrid aircon systems also won’t need regassing in the same manner as older petrol/diesel cars, but that’s probably a tangent for this thread!

Automotive systems also have flexible hoses which can contribute to the loss of refrigerant. Plus there are multiple connections to different components sealed by o-rings where household systems use hard lines and compression/soldered connections which don't really leak.

 

[SoliD]

Contacted Sub Cool to see what they can offer. I currently have an outside office that my wife uses and contemplating putting in one of the self install units, does anyone have any specific recommended manufacturers so I can see if it would be suitable as it's one of the insulated posh sheds with bi folds and a wooden cladding on the outside so should be a fairly easy install. @soundb0y how is yours going?

 

[Craigius]

Well after using mine upstairs in the hotter weather, having it fitted in both the front bedrooms, having both the units on set at 21 degrees leaving the doors open up stairs they clearly cool the whole of the upstairs and I can feel the cool air come down the stairs, the professional unit appears to be louder than the self fit unit until it settles down but it’s a lot quieter than a fan and having windows open especially with how busy my road is at the moment.
The professional Mitsubishi unit cools the room very fast on automatic and the external unit is almost silent so no complaint neighbours wish I had done it ages ago!

 

[SoliD]

Had Sub Zero quote me earlier this week with Jacob on Zoom. I've been quoted Mitsubishi electric 5.5k inc vat for a ducted system in the loft for 4 rooms (5.5KW), one wall mounted unit in the lounge (3.5KW) with a 7.2KW outer and another separate wall mount in an outdoor office. Just wondering how this compares to others in here.

 

[uncle_rufus]

Well I think ignoring the ducting I've always heard the rule of thumb that it's £1k + £1k per unit/room for a split system which would in your case suggest ~£4k but if the ducting stuff adds some complexity then maybe it's not too bad. Is the "separate wall mount in outdoor office" also connected to it's own separate outdoor unit, in which case the higher price would make sense as well...

 

[SoliD]

Well I think ignoring the ducting I've always heard the rule of thumb that it's £1k + £1k per unit/room for a split system which would in your case suggest ~£4k but if the ducting stuff adds some complexity then maybe it's not too bad. Is the "separate wall mount in outdoor office" also connected to it's own separate outdoor unit, in which case the higher price would make sense as well...

Yes outdoor office would be a completely separate unit. Quoted for 2 wall units in my office and master bedroom and this came in about 700 less. House is quite poorly insulated upstairs so having all 4 upstairs room connected is a real benefit. I've requested some quotes eelsewhere to see how it compares.

 

[happy_2008]

Had Sub Zero quote me earlier this week with Jacob on Zoom. I've been quoted Mitsubishi electric 5.5k inc vat for a ducted system in the loft for 4 rooms (5.5KW), one wall mounted unit in the lounge (3.5KW) with a 7.2KW outer and another separate wall mount in an outdoor office. Just wondering how this compares to others in here.

I had similar (1 loft unit for 3 rooms, 1 wall unit in dining & living room) but mine was around £4.6k. However, the two wall units are on the same wall as the outdoor unit so less work required for cabling etc.

 

[robj20]

If you get it ducted is there a way of controlling each room? Surely it would be possible via controllable vents.

 

[bazzabear]

You can definitely switch it off or on independantly in different rooms via vents. But different temperatures in different rooms might not be possible.

 

[happy_2008]

If you get it ducted is there a way of controlling each room? Surely it would be possible via controllable vents.

Only way is to manually spin the vent to close position. However, because its a loft unit it takes longer to cool down the room and obviously wont be as ice cold as an individual wall unit.

 

[bazzabear]

because its a loft unit it takes longer to cool down the room and obviously wont be as ice cold as an individual wall unit.

What's the logic behind that?